Pneumatolysis

Pneumatolysis (from the Greek pneuma = wind, air and lyein = to dissolve) is a form of rock transformation. It is particularly important for the formation of deposits .

It takes place in the course of the cooling and partial crystallization of magma under high pressure in the earth's interior. The volume of the magma decreases. At the same time, volatile substances such as water, carbon dioxide , hydrogen fluoride , hydrogen chloride , boron , beryllium as well as heavy and precious metals accumulate in it and cause the gas pressure of the melt to rise.

If this exceeds the ambient pressure, the aggressive acidic, silicon-containing gases penetrate deep into the surrounding rock. Due to the high temperatures, this is partially melted again. Changes in pressure lead to complex boiling and distillation processes of the penetrating gases, which lead to the formation of new minerals and ores. In this respect, pneumatolysis is a special case of contact metamorphosis .

Pneumatolytic processes lead to the formation of old men and characteristic dike deposits of tin , tungsten , molybdenum and copper ores . Typical gemstone formations are rubies , sapphires , emeralds and nephrites .